Helium is a "special" element in Group 18 because it does not have 8 valence electrons. Why doesn't helium have 8 valence electrons like all the other elements in group 18?

Helium is an element which belongs to a family called noble gas.
Among the noble gas element, helium is the only member with two (2) electrons.
Helium is a s-block element. S-block can only accommodate a maximum of 2 electrons. The two (2) electrons that helium has complete its outermost shell as seen from its electronic configuration below:
Since the outermost shell of helium is completely filled, it is thus included in the noble gas family (i.e group 18).
Other members of the this group include: Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn)
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